Microtubule Dynamic Toxicity

The drug taxol, extracted from the bark of yew trees, has the opposite effect of the drug colchicine, an alkaloid from autumn crocus. Taxol binds tightly to microtubules and stabilizes them. When taxol is added to cells, it causes much of the free tubulin to assemble into microtubules. In contrast, colchicine prevents microtubule formation. Taxol is just as disruptive to dividing cells as colchicine, and both are used as anticancer drugs. Based on your knowledge of microtuble dynamics, suggest why both drugs are toxic to dividing cells despite their opposite actions.

Solution Preview

Microtubules play a critical role in cell division in the form of spindle assembly. The mitotic spindle is the attachment site for the assembly of chromosomes at metaphase, and then during anaphase provides the mechanical means of chromosome segregation. Correct spindle assembly is thus necessary for the cell to undergo mitosis; without it, the cells fail to pass the necessary cell cycle checkpoint, enter mitotic arrest and eventually die or undergo apoptosis.
<br>
<br>Mitotic spindle function is a complex and dynamic process involving microtubule assembly and disassembly. At the start ...